PLS ANSWER QUICK Index fossils help scientists estimate the age of a rock because index fossil species only existed for a relatively short time. What happened to the species that are now used as index fossils.
1. They became extinct
2.They changed diets
3.They hid in marine sediments
4.They migrated to new environments

They became extinct.

Explanation:

The text says that index fossil species only existed for a relatively short time. If they don't exist anymore, that means that they are extinct.

1. They became extinct

they became extinct and lived for a distinct period of time which means that and sediment/ fossils found alongside these index fossils would be from the same time period

the answer will be a) proteins i believe

step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.